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1.
Hernia ; 28(3): 913-924, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38761301

ABSTRACT

PURPOSE: We studied the effectiveness of biomechanically calculated abdominal wall reconstructions for incisional hernias of varying complexity in an open, prospective observational registry trial. METHODS: From July 1st, 2017 to December 31st, 2020, four hospitals affiliated with the University of Heidelberg recruited 198 patients with complex incisional hernias. Hernias were repaired using biomechanically calculated reconstructions and materials classified on their gripping force towards cyclic load. This approach determines the required strength preoperatively based on the hernia size, using the Critical Resistance to Impacts related to Pressure. The surgeon is supported in reliably determining the Gained Resistance, which is based on the mesh-defect-area-ratio, as well as other mesh and suture factors, and the tissue stability. Tissue stability is defined as a maximum distension of 1.5 cm upon a Valsalva maneuver. In complex cases, a CT scan of the abdomen can be used to assess unstable tissue areas both at rest and during Valsalva's maneuver. RESULTS: Larger and stronger gripping meshes were required for more complex cases to achieve a durable repair, especially for larger hernia sizes. To achieve durable repairs, the number of fixation points increased while the mesh-defect area ratio decreased. Performing these repairs required more operating room time. The complication rate remained low. Less than 1% of recurrences and low pain levels were observed after 3 years. CONCLUSIONS: Biomechanical stability, defined as the resistance to cyclic load, is crucial in preventing postoperative complications, including recurrences and chronic pain.


Subject(s)
Herniorrhaphy , Incisional Hernia , Registries , Surgical Mesh , Humans , Incisional Hernia/surgery , Prospective Studies , Female , Male , Herniorrhaphy/methods , Middle Aged , Aged , Biomechanical Phenomena , Abdominal Wall/surgery , Follow-Up Studies
2.
Clin Biomech (Bristol, Avon) ; 82: 105253, 2021 02.
Article in English | MEDLINE | ID: mdl-33401197

ABSTRACT

BACKGROUND: Incisional hernia repair is burdened with recurrence, pain and disability. The repair is usually carried out with a textile mesh fixed between the layers of the abdominal wall. METHODS: We developed a bench test with low cyclic loading. The test uses dynamic intermittent strain resembling coughs. We applied preoperative computed tomography of the abdomen at rest and during Valsalva's maneuver to the individual patient to analyze tissue elasticity. FINDINGS: The mesh, its placements and overlap, the type and distribution of fixation elements, the elasticity of the tissue of the individual and the closure of the abdominal defect-all aspects influence the reconstruction necessary. Each influence can be attributed to a relative numerical quantity which can be summed up into a characterizing value. The elasticity of the tissues within the abdominal wall of the individual patient can be assessed with low-dose computed tomography of the abdomen with Valsalva's maneuver. We established a procedure to integrate the results into a surgical concept. We demonstrate potential computer algorithms using non-rigid b-spline registration and artificial intelligence to further improve the evaluation process. INTERPRETATION: The bench test yields relative values for the characterization of hernia, mesh and fixation. It can be applied to patient care using established procedures. The clinical application in the first ninety-six patients shows no recurrences and reduced pain levels after one year. The concept has been spread to other surgical groups with the same results in another fifty patients. Future efforts will make the abdominal wall reconstruction more predictable.


Subject(s)
Incisional Hernia/surgery , Mechanical Phenomena , Pressure , Adult , Artificial Intelligence , Biomechanical Phenomena , Elasticity , Female , Humans , Image Processing, Computer-Assisted , Incisional Hernia/diagnostic imaging , Male , Middle Aged , Prostheses and Implants , Recurrence , Surgical Mesh , Tomography, X-Ray Computed
3.
Chem Commun (Camb) ; 52(77): 11524-11526, 2016 Sep 20.
Article in English | MEDLINE | ID: mdl-27722464

ABSTRACT

Memory effects in Li-ion battery materials have been explained on the basis of the thermodynamics of many-particles body, however the role of the (de-)intercalation kinetics is not yet clear. We demonstrate that kinetic aspects, specifically Li-ion mobility, are determining the magnitude of the memory effect in TiO2 by studying samples with different levels of oxygen vacancies.

4.
Neurodegener Dis ; 11(4): 194-205, 2013.
Article in English | MEDLINE | ID: mdl-22797329

ABSTRACT

Tauopathies, characterized by hyperphosphorylation and aggregation of tau protein, include frontotemporal dementias and Alzheimer's disease. To explore disease mechanisms and investigate potential treatments, we generated a transgenic (tg) mouse line overexpressing human tau441 with V337M and R406W mutations. Biochemical characterization of these TMHT (Thy-1 mutated human tau) mice showed a significant increase in human transgene expression relative to endogenous murine tau by Western blot and multi-array immunosorbent assay. Only soluble total tau and phosphorylated tau (ptau at residue Thr(181), Ser(199), Thr(231) and Thr(235)), but not insoluble total tau and ptau were increased. Application of the Phospho-Tau SRM assay revealed that phosphorylation at Ser(396) and Ser(404) in soluble tau in the presence of the R406W mutation was at baseline levels in the cortex of TMHT mice compared to non-tg littermates. Histological analyses showed a progressive increase in human tau protein in the amygdala over age, while hippocampal tau levels remained constant from 2 months onwards. Behavioral testing of TMHT mice in the Morris water maze revealed a distinct progressive spatial learning impairment starting already at 5 months of age. Furthermore, we showed that the TMHT mice have early olfactory deficits. These impairments are unbiased by any motor disturbance or lack of motivation. Our results prove that combination of the V337M and R406W mutations of tau accelerates human tau phosphorylation and induces tau pathology as well as cognitive deficits, making this model a suitable tool for basic research on tau as well as in vivo drug testing.


Subject(s)
Behavior, Animal/physiology , Mutation/genetics , Tauopathies/metabolism , tau Proteins/metabolism , Aging , Animals , Disease Models, Animal , Humans , Mice , Mice, Transgenic , Phosphorylation/physiology , Tauopathies/pathology , tau Proteins/genetics
5.
Opt Express ; 18(11): 11316-26, 2010 May 24.
Article in English | MEDLINE | ID: mdl-20588993

ABSTRACT

We report the realization of coherent electro-optical detection of nanosecond terahertz (THz) pulses from an optical parametric oscillator, which is pumped by a Q-switched nanosecond Nd:YVO4 laser at 1064 nm and emits at approximately 1.5 THz. The beam profile and wavefront of the THz beam at focus are electro-optically characterized toward the realization of a real-time THz camera. A peak dynamic range of approximately 37 dB/radical Hz is achieved with single-pixel detection.


Subject(s)
Electronics/instrumentation , Micro-Electrical-Mechanical Systems/instrumentation , Optical Devices , Oscillometry/instrumentation , Equipment Design , Equipment Failure Analysis , Terahertz Radiation
6.
Br J Surg ; 95(10): 1257-63, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18720469

ABSTRACT

BACKGROUND: Patients with primary rectal cancer undergoing low anterior resection are often reconstructed using a pouch procedure. The aim of this trial was to compare colon J pouch (CJP) with transverse coloplasty pouch (TCP) reconstruction with regard to functional results, perioperative mortality and morbidity. As there is considerable uncertainty over the true anastomotic leak rate in patients with a TCP, the study analysed short-term outcome data. METHODS: Elective patients suitable for either procedure after sphincter-saving low anterior resection were eligible. Randomization took place during surgery. The primary endpoint was the rate of late evacuation problems after 2 years; secondary endpoints were anastomotic leak rate, perioperative morbidity and mortality. RESULTS: Between 21 October 2002 and 5 December 2005, 149 patients were randomized. All 76 patients randomized to TCP had the procedure compared with 68 of the 73 patients (93 percent) randomized to CJP. Both groups were comparable with regard to demographic and clinical characteristics. Surgical complications (CJP: 19 percent; TCP: 18 percent) and the overall anastomotic leak rate (8 percent) were equally distributed in both groups. CONCLUSION: This trial demonstrated a comparable early outcome for TCP and CJP. This contradicts previous reports suggesting a higher leak rate after TCP. REGISTRATION NUMBER: ISRCTN78983587 (http://www.controlled-trials.com).


Subject(s)
Colonic Pouches , Rectal Neoplasms/surgery , Rectum/surgery , Adult , Aged , Aged, 80 and over , Anastomosis, Surgical , Female , Humans , Length of Stay , Male , Middle Aged , Preoperative Care , Rectal Neoplasms/radiotherapy , Surgical Wound Dehiscence/etiology , Treatment Outcome
7.
Unfallchirurg ; 111(6): 387-94, 2008 Jun.
Article in German | MEDLINE | ID: mdl-18351312

ABSTRACT

INTRODUCTION: The therapy of the midshaft clavicle fracture, in particular dislocated midshaft fractures, remains controversial. Therefore the objective of this study was to obtain data about the current treatment for midshaft clavicle fractures. METHODS: In a countrywide anonymous survey 240 German orthopaedic trauma departments were asked about their diagnostic and therapeutic procedures for midshaft clavicle fractures. A total of 142 questionnaires (59%) were returned and evaluated. RESULTS: More than 80% of the hospitals dispense with a standardised fracture classification for midshaft fractures. Simple fractures are generally conservatively treated, in the majority using a figure-of-eight bandage (88%). On average 26% of all clavicle fractures are operatively stabilized, independent of whether the treatment was performed at a trauma centre or any other hospital (p=0.45). Indications for operative treatment of midshaft fractures include severe additional injuries in the shoulder region (81-95%), young and active adults (52-64%) and dislocated midshaft fractures (56-75%). All departments use plate fixation for midshaft fractures; in particular the reconstruction plate (56%) is most frequently applied. Alternatively, if the fracture pattern is considered suitable for intramedullary fixation, this procedure is performed by 43% of the clinics, although this operative technique is used significantly more often in trauma centres (55%) than in other hospitals (31%) (p=0.01). CONCLUSION: This survey demonstrates a high rate (26%) of German trauma hospitals operating clavicular midshaft fractures. This result is consistent with recently published studies showing better results for operative treatment of dislocated midshaft clavicular fractures compared to conservative therapy.


Subject(s)
Clavicle/injuries , Clavicle/surgery , Fracture Fixation/statistics & numerical data , Fractures, Bone/diagnosis , Fractures, Bone/surgery , Immobilization/statistics & numerical data , Practice Patterns, Physicians'/statistics & numerical data , Trauma Centers/statistics & numerical data , General Surgery , Germany , Humans , Physicians/statistics & numerical data
8.
Gut ; 54(7): 944-9, 2005 Jul.
Article in English | MEDLINE | ID: mdl-15951539

ABSTRACT

BACKGROUND AND AIMS: Conflicting results exist about the presence of Mycobacterium avium subspecies paratuberculosis (MAP) specific IS900 DNA in Crohn's disease (CD) tissues. Therefore, we examined IS900 in a large number of gut samples from patients with CD (n = 100) and ulcerative colitis (UC, n = 100), and in non-inflamed control tissues (nIBD, n = 100). We hypothesised that IS900 DNA detection might be associated with distinct clinical phenotypic characteristics in CD. METHODS: The prevalence of MAP DNA in surgically resected tissues was examined using a mechanical-enzymatic disruption technique and nested IS900 specific polymerase chain reaction (PCR). CD patients were stratified according to the criteria of the Vienna classification and other clinical characteristics. RESULTS: IS900 PCR detection rate was significantly higher in CD tissue samples (52%) than in UC (2%) or nIBD (5%) specimens (p<0.0001). In CD patients, IS900 DNA was detected in samples from both diseased small bowel (47%) as well as from the colon (61%). No firm association between MAP specific IS900 detection rates and clinical phenotypic characteristics in CD could be established. However, corticosteroid medication constituted a factor which tended to have a negative influence on IS900 DNA detection rates in CD (p<0.01). CONCLUSIONS: The presence of MAP specific IS900 DNA is a predominant feature of CD. Therapeutic intervention against MAP might represent a potential target for disease mitigation in Crohn's disease.


Subject(s)
Crohn Disease/microbiology , Paratuberculosis/complications , Adult , Aged , Colitis, Ulcerative/microbiology , DNA, Bacterial/analysis , Female , Humans , Intestines/microbiology , Male , Middle Aged , Mycobacterium avium subsp. paratuberculosis/isolation & purification , Polymerase Chain Reaction/methods
9.
Opt Express ; 13(14): 5353-62, 2005 Jul 11.
Article in English | MEDLINE | ID: mdl-19498529

ABSTRACT

We present a detailed experimental and theoretical study of terahertz (THz) generation and beam propagation in an optoelectronic THz system consisting of a large-area (ZnTe) electro-optic emitter and a standard electro-optic detector, and provide a comparison to typical biased GaAs emitters. As predicted by theory, in the absence of saturation the generated THz pulse energy is inversely proportional to the area of the optical pump beam incident on the emitter, although the detected on-axis electric field amplitude of the subsequently focused THz beam is practically independent of this area. This latter result promotes the use of larger emitter crystals in amplifier-laser-based THz systems in order to minimize saturation effects. Moreover, the generation of an initially larger THz beam also provides improved spatial resolution at intermediate foci between emitter and detector.

10.
Int J Dev Neurosci ; 19(3): 279-85, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11337196

ABSTRACT

Fructose-1,6-bisphosphatase is one of the key enzymes in the gluconeogenic pathway predominantly occurring in liver, kidney and muscle. In the brain, fructose-1,6-bisphosphatase has been suggested to be an astrocyte-specific enzyme but the functional importance of glyconeogenesis in the brain is still unclear. To further elucidate the cellular source of fructose-1,6-bisphosphatase in the brain, non-radioactive in situ hybridizations were performed using digoxigenin-labeled RNA probes based on the sequence of recently cloned rat liver and muscle fructose-1,6-bisphosphatase cDNAs. In situ hybridization using a riboprobe for the liver isoform revealed a location of the hybridization signal mainly in neurons, while rat muscle fructose-1,6-bisphosphatase mRNA was detected in both neurons and astrocytes in the hippocampal formation and in layer I of the cerebral cortex.RT-PCR using RNA preparations of rat astrocytes, neurons, and adult whole brain demonstrated a localization of liver fructose-1,6-bisphosphatase mRNA isoform in neurons but not in astrocytes. The muscle fructose-1,6-bisphosphatase mRNA isoform could be detected by RT-PCR in total rat brain, astrocytic, and neuronal mRNA preparations. The isoforms of fructose-1,6-bisphosphatase mRNA seemingly demonstrate a distinct cellular expression pattern in rat brain suggesting a role of glyconeogenesis in both neurons and glial cells.


Subject(s)
Cholinergic Fibers/enzymology , Fructose-Bisphosphatase/genetics , Gluconeogenesis/physiology , Isoenzymes/genetics , Prosencephalon/metabolism , Animals , Astrocytes/chemistry , Astrocytes/enzymology , Denervation , Fructose-Bisphosphatase/metabolism , Gene Expression Regulation, Enzymologic , Glial Fibrillary Acidic Protein/analysis , In Situ Hybridization , Isoenzymes/metabolism , Male , Neurons/enzymology , Prosencephalon/cytology , RNA Probes , RNA, Messenger/analysis , Rats , Rats, Wistar
11.
J Clin Oncol ; 19(6): 1787-94, 2001 Mar 15.
Article in English | MEDLINE | ID: mdl-11251010

ABSTRACT

PURPOSE: Adjuvant postoperative treatment with fluorouracil (5-FU) and levamisole in curatively resected stage III colon cancer significantly reduces the risk of cancer recurrence and improves survival. Biochemical modulation of 5-FU with leucovorin has resulted in increased remission rates in metastatic colorectal cancer, thus reflecting an increased tumor-cell kill. The impact of 5-FU plus leucovorin on survival and tumor recurrence was analyzed in comparison with the effects of 5-FU plus levamisole in the prospective multicentric trial adjCCA-01. PATIENTS AND METHODS: Patients with a curatively resected International Union Against Cancer stage III colon cancer were stratified according to T, N, and G category and randomly assigned to receive one of the two adjuvant treatment schemes: 5-FU 400 mg/m(2) body-surface area intravenously in the first chemotherapy course, then 450 mg/m(2) x 5 days; 12 cycles, plus leucovorin 100 mg/m(2) (arm A), or 5-FU plus levamisole (Moertel scheme; arm B). RESULTS: Six hundred eighty (96.9%) of 702 patients enrolled onto this study were eligible. After a median follow-up time of 46.5 months, the 5-FU plus leucovorin combination significantly improved disease-free survival (P =.037) and significantly decreased overall mortality (P =.0089) in comparison with 5-FU plus levamisole. In a multivariate proportional hazards model, adjuvant chemotherapy emerged as a significant prognostic factor for survival (P =.0059) and disease-free survival (P =.03). Adjuvant treatment with 5-FU plus levamisole as well as with 5-FU plus leucovorin was generally well tolerated; only a minority of patients experienced grade 3 and 4 toxicities. CONCLUSION: After a curative resection of a stage III colon cancer, adjuvant treatment with 5-FU plus leucovorin is generally well tolerated and significantly more effective than 5-FU plus levamisole in reducing tumor relapse and improving survival.


Subject(s)
Antimetabolites, Antineoplastic/administration & dosage , Colonic Neoplasms/drug therapy , Fluorouracil/administration & dosage , Leucovorin/administration & dosage , Adjuvants, Immunologic/administration & dosage , Adjuvants, Immunologic/pharmacology , Aged , Antimetabolites, Antineoplastic/pharmacology , Chemotherapy, Adjuvant , Colonic Neoplasms/surgery , Combined Modality Therapy , Female , Fluorouracil/pharmacology , Humans , Infusions, Intravenous , Leucovorin/pharmacology , Levamisole/administration & dosage , Levamisole/pharmacology , Male , Middle Aged , Neoplasm Recurrence, Local , Survival Analysis , Treatment Outcome
12.
Opt Express ; 9(12): 616-21, 2001 Dec 03.
Article in English | MEDLINE | ID: mdl-19424298

ABSTRACT

We investigate dark-field imaging in the terahertz (THz) fre-quency regime with the intention to enhance image contrast through the analysis of scattering and diffraction signatures. A gold-on-TPX test structure and an archived biomedical tissue sample are examined in conventional and dark-field transmission geometry. In particular, the capability of the technique for tumor detection is addressed.

13.
J Neural Transm (Vienna) ; 108(12): 1457-74, 2001.
Article in English | MEDLINE | ID: mdl-11810408

ABSTRACT

To reveal whether an extract of Ginkgo biloba (EGb761) may affect streptozotocin (STZ)-induced impairments in brain glucose metabolism, autoradiographies of [3H]cytochalasin-B binding to the total population of glucose transporters, [125I]insulin binding to insulin receptors, [3H]glyburide binding to sulfonylurea receptors, and radioactive in situ hybridization for GLUT3 mRNA were carried out in hippocampal brain sections of adult rats that have additionally been divided into good performers (GP) and poor performers (PP) by behavioural tests before the experiments. The STZ-induced increases in hippocampal [3H]cytochalasin-B binding to (total) glucose transporters returned to almost normal values following EGb761 treatment, regardless of the experimental animal group (GP or PP) tested. Similarly, the STZ-mediated enhancements in hippocampal insulin receptor binding of GP rats were partially compensated by the treatment with EGb761. The data suggest beneficial effects of EGb671 on impaired brain glucose metabolism, at least under the experimental conditions used in the study presented.


Subject(s)
ATP-Binding Cassette Transporters , Glucose/metabolism , Hippocampus/metabolism , Monosaccharide Transport Proteins/metabolism , Nerve Tissue Proteins , Neurons/metabolism , Neuroprotective Agents/pharmacology , Plant Extracts/pharmacology , Potassium Channels, Inwardly Rectifying , Receptor, Insulin/metabolism , Animals , Binding Sites/drug effects , Binding Sites/physiology , Cytochalasin B/pharmacokinetics , Ginkgo biloba/chemistry , Glucose Transporter Type 3 , Hippocampus/drug effects , Hippocampus/physiopathology , Male , Monosaccharide Transport Proteins/drug effects , Neurons/drug effects , Potassium Channels/drug effects , Potassium Channels/metabolism , Radioligand Assay , Rats , Rats, Wistar , Receptor, Insulin/drug effects , Receptors, Drug/drug effects , Receptors, Drug/metabolism , Streptozocin/pharmacology , Sulfonylurea Receptors , Up-Regulation/drug effects , Up-Regulation/physiology
14.
Ann N Y Acad Sci ; 920: 256-8, 2000.
Article in English | MEDLINE | ID: mdl-11193160

ABSTRACT

It has been hypothesized that a central even in the early pathogenesis of sporadic Alzheimer disease (SAD) is the dysfunction of the neuronal insulin receptor signal transduction. To prove this, this receptor was inhibited by a triplicate icv application of STZ. Insulin binding sites were upregulated as in SAD. With respect to glucose transport proteins, detailed investigations are necessary.


Subject(s)
ATP-Binding Cassette Transporters , Alzheimer Disease/physiopathology , Brain/physiopathology , Insulin/metabolism , Neurons/physiology , Potassium Channels, Inwardly Rectifying , Receptor, Insulin/antagonists & inhibitors , Streptozocin/pharmacology , Alzheimer Disease/pathology , Animals , Autoradiography , Brain/drug effects , Brain/physiology , Cerebral Ventricles/drug effects , Cerebral Ventricles/physiology , Cerebral Ventricles/physiopathology , Disease Models, Animal , Glyburide/metabolism , Injections, Intraventricular , Iodine Radioisotopes , Neurons/drug effects , Potassium Channels/drug effects , Potassium Channels/metabolism , Rats , Receptors, Drug/drug effects , Receptors, Drug/metabolism , Streptozocin/administration & dosage , Sulfonylurea Receptors
15.
Semin Oncol ; 25(5 Suppl 12): 32-4, 1998 Oct.
Article in English | MEDLINE | ID: mdl-9865710

ABSTRACT

The recommended weekly dose and the maximum tolerated weekly dose of docetaxel (Taxotere; Rhône-Poulenc Rorer, Antony, France) have yet to be determined. We report that a weekly dose of up to 40 mg/m2 docetaxel for 6 weeks is active in pretreated patients with metastatic breast cancer. From a preliminary study, this dose-dense schedule appears to induce less hematologic toxicity than a schedule of 100 mg/m2 every 3 weeks while achieving similar response rates and may represent a valuable alternative involving a shorter treatment time in the palliative therapy of advanced disease in higher-risk patients. The dose-dense weekly administration of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) also appears to be active, although the toxicity profiles of the two taxanes may differ.


Subject(s)
Antineoplastic Agents, Phytogenic/administration & dosage , Breast Neoplasms/drug therapy , Paclitaxel/analogs & derivatives , Palliative Care , Taxoids , Antineoplastic Agents, Phytogenic/therapeutic use , Docetaxel , Drug Administration Schedule , Humans , Paclitaxel/administration & dosage , Paclitaxel/therapeutic use
16.
Tissue Antigens ; 51(3): 270-5, 1998 Mar.
Article in English | MEDLINE | ID: mdl-9550327

ABSTRACT

Genetic hemochromatosis (GH) is closely associated with genes of the major histocompatibility complex (MHC) on chromosome 6. Recently, a candidate gene for GH, with structural similarities to MHC class I genes, designated HLA-H and presently named HFE, has been cloned. The HFE gene is localized telomeric to the MHC and several reports have indicated that the HFE gene is mutated in GH patients. In the present study we have analyzed the relationship of HFE gene variants and disease manifestation in GH patients and family members. Fifty-seven patients with GH, 73 family members and 153 healthy blood donors were studied for the amino acid dimorphism at codon 63 (His63Asp=H63D) and codon 282 (Cys282Tyr= C282Y) of the HFE gene. The codon 63 and 282 dimorphism were defined by PCR amplification of genomic DNA samples and restriction enzyme digestion using RsaI/SnaBI for C282Y and BclI/MboI for H63D. Ferritin, transferrin serum levels and total iron-binding capacity were determined prior to therapeutic intervention. The Tyr-282 substitution occurred in 53 (93%) of patients compared with 8 (5.2%) of controls (OR=169, P<0.0001). Fifty-one (90%) patients were Tyr-282 homozygous. In contrast, the Asp-63 substitution was present in 5 (8.8%) of the patients compared with 34 (22%) of controls (OR=0.39, P=NS) with none of the patients being homozygous. In Tyr-282 homozygous GH patients serum ferritin levels, transferrin saturation, liver iron and liver iron index were elevated significantly compared to Tyr-282-negative patients, whereas no difference was observed between Tyr/Cys-282 heterozygous and Tyr-282-negative patients.


Subject(s)
Aspartic Acid/genetics , Codon , Cysteine/genetics , HLA Antigens/genetics , Hemochromatosis/genetics , Histidine/genetics , Histocompatibility Antigens Class I/genetics , Membrane Proteins , Tyrosine/genetics , Female , Genotype , Germany , Hemochromatosis Protein , Humans , Male , Point Mutation , Polymorphism, Genetic
17.
Theor Popul Biol ; 54(3): 213-26, 1998 Dec.
Article in English | MEDLINE | ID: mdl-9878601

ABSTRACT

Individual based, stochastic forest patch models have the potential to realistically describe forest dynamics. However, they are mathematically intransparent and need long computing times. We simplified such a forest patch model by aggregating the individual trees on many patches to height-structured tree populations with theoretical random dispersions over the whole simulated forest area. The resulting distribution-based model produced results similar to those of the patch model under a wide range of conditions. We concluded that the height- structured tree dispersion is an adequate population descriptor to capture the stochastic variability in a forest and that the new approach is generally applicable to any patch model. The simplified model required only 4.1% of the computing time needed by the patch model. Hence, this new model type is well-suited for applications where a large number of dynamic forest simulations is required.


Subject(s)
Models, Biological , Monte Carlo Method , Numerical Analysis, Computer-Assisted , Population Dynamics , Stochastic Processes , Trees/growth & development , Bias , Climate , Ecosystem , Population Density , Reproducibility of Results , Time Factors , Trees/anatomy & histology
18.
Int J Dev Neurosci ; 16(7-8): 675-90, 1998.
Article in English | MEDLINE | ID: mdl-10198816

ABSTRACT

To address the question whether the changes in cortical glucose metabolism observed in patients with Alzheimer's disease are interrelated with, or consequences of, basal forebrain cholinergic cell loss, an experimental approach was employed to produce cortical cholinergic dysfunction in rat brain by administration of the cholinergic immunotoxin 192IgG-saporin. [14C]D-glucose utilization in brain homogenates, D-glucose-displaceable [3H]cytochalasin B binding to glucose transporters (GLUT). Northern and Western analyses, as well as in vivo [14C]2-deoxyglucose autoradiography were used to quantify the regional glucose metabolism. Basal forebrain cholinergic lesion resulted in transient increases in glucose transporter binding in cortical regions displaying reduced acetylcholinesterase activity, already detectable seven days after lesion with peak values around 30 days post lesion. Western analysis revealed that the changes in total glucose transporter binding are mainly due to changes in the GLUT3 subtype only, while the levels of GLUT1 and GLUT3 mRNA (Northern analysis) were not affected by cholinergic lesion. Both immunocytochemistry and in situ hybridization demonstrated preferential localizations of GLUT1 on brain capillaries and GLUT3 on neurons, respectively. A lesion-induced transient decrease in [14C]D-glucose utilization seven days post lesion was detected in the lesion site, whereas cholinoceptive cortical regions were not affected. In vivo [14C]deoxyglucose uptake was transiently increased in cholinoceptive cortical regions and in the lesion site being highest between three to seven days after lesion. The cholinergic lesion-induced transient up-regulation of cortical glucose transporters and deoxyglucose uptake reflects an increased glucose demand in regions depleted by acetylcholine suggesting functional links between cortical cholinergic activity and glucose metabolism in cholinoceptive target regions.


Subject(s)
Antibodies, Monoclonal/toxicity , Cholinergic Agents/toxicity , Glucose/metabolism , Immunotoxins/toxicity , Prosencephalon/drug effects , Receptors, Cholinergic/drug effects , Animals , Autoradiography , Blotting, Northern , Blotting, Western , Cytochalasin B/metabolism , Male , Monosaccharide Transport Proteins/metabolism , N-Glycosyl Hydrolases , Prosencephalon/metabolism , Radioligand Assay , Rats , Rats, Wistar , Receptors, Cholinergic/metabolism , Ribosome Inactivating Proteins, Type 1 , Saporins
19.
Neurochem Int ; 30(6): 557-63, 1997 Jun.
Article in English | MEDLINE | ID: mdl-9152997

ABSTRACT

The aim of this study was to determine whether L-glutamate, a major excitatory transmitter in the cerebral cortex, modulates the proteolytic cleavage of the amyloid precursor protein (APP) in the brain through specific receptor activation. Native rat brain cerebral cortical slices were stimulated either with L-glutamate or various glutamate receptor agonists, and the soluble APP derivatives released into the incubation medium were assayed by Western blot analysis. Immunoprecipitation with specific antibodies revealed that in the medium only secretory forms of APP lacking intact C-terminus were present, whereas in the brain slices both C- and N-terminal intact APP products were detectable. L-glutamate induced the release of secretory APP from cortical slices in a concentration-dependent but biphasic manner, with the highest release at 50 microM L-glutamate and smaller effects at higher glutamate concentrations. To determine whether the effect of L-glutamate is mediated through distinct glutamate receptor subtypes, brain slices were incubated in the presence of various specific glutamate receptor agonists. Activation of the alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA) receptor with 50 nM (RS)-bromohomoibotenic acid resulted in a reduced release of secretory APP by 17% +/- 3 (P < 0.01, one tailed Student's t-test) compared to the incubation without any drug. Stimulation of the metabotropic glutamate receptor with 50 nM (2S,3S,4S)-alpha-(carboxycyclopropyl)-glycine (L-CCG-I) led to an enhanced release of secretory APP by 39% +/- 3 (P < 0.001), whereas activation of the N-methyl-D-aspartate (NMDA) receptor with 50 nM (1R,3R)-1-aminocyclopentane-1,3-dicarboxylic acid ((1R,3R)-ACPD) did not significantly change the secretion of APP compared to the incubation without any drug. The data suggest that: (i) cortical glutamatergic neurotransmission is involved in APP metabolism; and (ii) the stimulation of APP cleavage in cerebral cortical brain slices is mainly mediated by the metabotropic but not the NMDA glutamate receptor subtype, whereas the AMPA receptor subtype seems to inhibit the secretory path of APP processing.


Subject(s)
Amyloid beta-Protein Precursor/metabolism , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Glutamic Acid/pharmacology , Animals , Excitatory Amino Acid Agonists/pharmacology , Glycosylation , Immunosorbent Techniques , Kinetics , Male , Rats , Rats, Wistar , Receptors, AMPA/drug effects , Receptors, AMPA/physiology , Receptors, Metabotropic Glutamate/drug effects , Receptors, Metabotropic Glutamate/physiology , Receptors, N-Methyl-D-Aspartate/drug effects , Receptors, N-Methyl-D-Aspartate/physiology
20.
Semin Oncol ; 23(6 Suppl 16): 32-4, 1996 Dec.
Article in English | MEDLINE | ID: mdl-9007118

ABSTRACT

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) has been studied primarily on a 3-week schedule as a 3-, 24-, or 96-hour infusion at doses ranging from 135 to 250 mg/m2. The observed toxicity profile seems to be both dose and schedule dependent. Dose densification of paclitaxel given weekly over 6 weeks on a split-dose schedule for an overall increase in dose intensity was thought to improve the therapeutic index of paclitaxel in a variety of advanced malignancies and to be suitable for outpatient administration. For this study, chemotherapy consisted of a weekly 1-hour infusion of paclitaxel at a starting dose of 40 mg/m2/wk for 6 weeks, followed by a 2- to 3-week interval. Paclitaxel dosage was escalated in 10 mg/m2/wk increments in subsequent patients, to a maximum dosage of 90 mg/m2/wk. Intravenous dexamethasone, cimetidine, clemastine, and ondansetron were administered immediately before the paclitaxel infusion. Fifty patients participated in the study. The male to female ratio was 21 to 29, the median age was 53.2 years (age range, 33 to 74), and the median performance status was 1. All patients were chemotherapeutically pretreated. Overall response included five complete responses (10%), 15 partial responses (30%), 19 no change (38%), and 11 disease progressions (22%). Median dose intensity was 410 mg/m2/6 wk (range, 200 to 540 mg/m2/6 wk). Hematologic toxicity was mild, with no grade 3 or 4 toxicity up to 90 mg/m2/wk. No hypersensitivity reactions or neurologic or cardiac toxicities were documented. Dose-densified, weekly paclitaxel is concluded to be active in a variety of pretreated tumor entities. The overall low hematologic and peripheral toxicity profile suggests that further dose intensification of weekly paclitaxel and/or combination with other cytotoxic agents (eg, cisplatin/carboplatin, ifosfamide, etoposide) may be warranted. Paclitaxel can be given safely in the outpatient setting. Paclitaxel 90 mg/m2/wk is recommended for single-agent treatment. Dose-densified paclitaxel may be considered a valuable and promising alternative to standard 3-week treatment, with further options possible in combination chemotherapy.


Subject(s)
Antineoplastic Agents, Phytogenic/administration & dosage , Neoplasms/drug therapy , Paclitaxel/administration & dosage , Adult , Aged , Anti-Allergic Agents/administration & dosage , Antiemetics/administration & dosage , Antineoplastic Agents, Phytogenic/toxicity , Cimetidine/administration & dosage , Clemastine/administration & dosage , Dexamethasone/administration & dosage , Drug Administration Schedule , Female , Histamine H2 Antagonists/administration & dosage , Humans , Infusions, Parenteral , Male , Middle Aged , Ondansetron/administration & dosage , Paclitaxel/toxicity
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